Leptospirose : Symptômes, transmission et prévention de cette maladie en hausse

Recent health alerts in France have focused on a resurgence of leptospirosis, a bacterial infection that can spread between animals and humans. In mid-January, the Bourgogne-Franche-Comté Regional Health Agency reported three confirmed human cases, all affecting individuals between the ages of 25 and 35 who had recently purchased rats from the same pet store. Earlier in January, a dog in Brittany succumbed to the disease.

Understanding Leptospirosis

Leptospirosis is a disease requiring mandatory reporting in France, and has been linked to several recent incidents. The severity of these cases prompted the national emergency veterinary number, 3115, to issue a public alert on January 21st regarding this relatively unknown zoonosis – a disease transmissible from animals to humans.

Rising Incidence

While relatively rare in mainland France, the number of leptospirosis cases has been increasing since 2014. Santé publique France reports an average of 300 to 600 cases annually. The incidence rate is approximately 1 case per 100,000 inhabitants in mainland France, but is significantly higher – 12 to 70 times greater – in French overseas territories, posing a substantial public health concern.

Did You Know? Worldwide, an estimated one million cases of leptospirosis occur each year, with over 10% resulting in death.

How Leptospirosis Spreads

Leptospirosis is caused by Leptospira bacteria, transmitted through the urine of infected animals. These bacteria can survive for extended periods in the environment, particularly in freshwater and muddy areas, according to the Institut Pasteur. Common animal carriers include rodents, insectivores, livestock such as cattle, horses, and pigs, and domestic pets like dogs.

The bacteria enter the body through wounds or mucous membranes after contact with contaminated urine or urine-soaked objects.

Symptoms and Severity

The incubation period for leptospirosis ranges from 5 to 14 days. Symptoms include high fever, chills, headache, red eyes, muscle and joint pain, and sometimes cough. The Institut Pasteur notes that while no single symptom is definitive, yellowing of the eyes (jaundice) and muscle pain are particularly indicative of the disease.

The illness can manifest in various forms, from a mild flu-like illness to severe multi-organ involvement with bleeding. A moderate case can progress to affect the kidneys, liver, brain, or lungs. In 20% of cases, it leads to a hemorrhagic syndrome. The most severe form, known as Weil’s syndrome, involves acute kidney failure, neurological complications (seizures, coma), and pulmonary or digestive bleeding, and can be fatal. Recovery from severe cases is prolonged, though typically without lasting effects, although eye problems can occur later.

Expert Insight: The non-specific nature of early leptospirosis symptoms – resembling the flu – highlights the importance of considering potential animal exposure in individuals presenting with these signs, particularly in areas where the disease is known to be present.

Diagnosis and Treatment

Diagnosis involves testing for the bacteria in blood or urine (PCR test) or detecting associated antibodies (serology). The disease can sometimes resolve on its own, but antibiotics are often recommended. Severe cases require hospitalization and antibiotic administration.

Prevention

Effective preventative measures include rodent control, drainage of floodwaters, and monitoring water sources from livestock areas. Individuals can reduce their risk by wearing gloves, goggles, and boots, and avoiding swimming in freshwater if they have open wounds, especially after heavy rainfall. A vaccine is available for those at higher risk, such as sewer workers, farmers, and sanitation workers.

Protecting Your Dog

To protect dogs – and their owners – the 3115 Urgences Vétérinaires recommends annual vaccination, avoiding stagnant water and muddy areas, practicing good hygiene after contact with wet environments, and seeking prompt veterinary care if unusual symptoms appear. Hundreds of canine leptospirosis cases are diagnosed annually in France, and the condition is considered an emergency. Without rapid treatment, 20 to 50% of severely affected dogs do not survive, and the mortality rate can reach 90 to 100%.

According to Pierre Fabing, a veterinarian at 3115, “Leptospirosis often begins with non-specific symptoms: fever, intense fatigue, pain, and weakness. This misleading characteristic can delay diagnosis in both dogs and humans.”

Frequently Asked Questions

What animals can transmit leptospirosis?

Rats, insectivores, livestock (cattle, horses, pigs), and domestic pets like dogs can all transmit the disease through their urine, according to the Institut Pasteur.

How long does it take for symptoms to appear after exposure?

The incubation period for leptospirosis is between 5 and 14 days.

Is leptospirosis always fatal?

While the severe form, Weil’s syndrome, can be fatal, many cases can be treated successfully with antibiotics, and some may even resolve on their own.

Given the increasing incidence of leptospirosis and the potential for serious complications, what steps can individuals take to better protect themselves and their pets in areas where the disease is prevalent?